Stephane Saj

Stephane Saj
Cirad - La recherche agronomique pour le développement | CIRAD · Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD)

PhD, environmental ecology, University of Helsinki
Currently working in French Guiana and West Indies. Topics : Setup, management, economic viability of cocoa based AFS

About

49
Publications
15,418
Reads
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Introduction
Stephane Saj currently works at the Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD). Researcher in the functioning and design of agroforestry systems aiming at increasing smallholder farmers livelihood, food diversity and security. Main topic: Sustainability of agroforestry systems and long-term production dynamics, functional traits and species diversity and use - trade-off between production, ecological and sociological services provided. Scientific specialty : Agronomy and soil sciences; Functional ecology and conservation ; Agroforestry.
Additional affiliations
April 2012 - present
Cirad - La recherche agronomique pour le développement
Position
  • Researcher
February 2005 - February 2008
University of Helsinki
Position
  • PhD Student
February 2005 - May 2006
University of Jyväskylä
Position
  • PhD Student

Publications

Publications (49)
Article
Full-text available
Viability of cocoa cultivation in French Guiana – a modeling approach Description of the subject. The cultivation of cocoa trees in French Guiana is currently experiencing a renewed level of interest and activity. A suitable framework is therefore needed to study the viability of this emerging area of cultivation. Objectives. To carry out an asse...
Method
Full-text available
Le cacao : de la cabosse aux fèves fermentées et séchées Retour d'expérience de récolte sur cacaoyers guiana en Guyane Française (année 2021)
Method
Full-text available
A small document to help growers and technicians to prune cocoa trees on the field. English version: p1 to p33 Un petit document pour soutenir sur le terrain les agriculteurs et tecniciens dans la taille des cacaoyers au champ. Version française : p34 à 66.
Technical Report
Full-text available
A short description of agroforestry systems based on main crops
Article
Plant diversification through crop rotation or agroforestry is a promising way to improve sustainability of agroecosystems. Nonetheless, criteria to select the most suitable plant communities for agroecosystems diversification facing contrasting environmental constraints need to be refined. Here, we compared the impacts of 24 different plant commun...
Article
Full-text available
Nutrient cycling in cocoa agroforestry systems (cAFS) is complex and poorly understood. To better understand the mass flow of carbon and nutrients into the soil sub-system under various contexts we quantified the mass flow of litterfall, its composition and seasonal variations in different agroforestry systems in Bokito (Central Cameroon). We studi...
Method
Full-text available
Méthode de reconnaissance visuelle des manques nutritionnels sur feuilles de cacaoyers Visual method (pictures) to recognize nutrient deficiencies on cocoa tree leaves
Article
Nutrient cycling in cocoa agroforestry systems (cAFS) is complex and poorly understood. To better understand the mass flow of carbon and nutrients into the soil subsystem under various contexts we quantified the mass flow of litterfall, its composition and seasonal variations in different agroforestry systems in Bokito (Central Cameroon). We studie...
Article
Full-text available
Combining mixed trees with cocoa trees in so-called cocoa agroforestry systems is emerging as a viable option for regenerating cocoa cropping in Africa. Pure cocoa crop stands currently prevail in these areas but are running out of steam. Technical solutions are therefore urgently needed to stabilize cocoa-growing areas, reduce pressure on forests...
Article
Full-text available
La agroforestería, que asocia árboles con cacaoteros, parece ser una opción posible para renovar el cultivo del cacao en África. El cultivo puro de árboles de cacao, dominante, no es sostenible y el potencial productivo disminuye con el tiempo. Por lo tanto, es urgente encontrar soluciones técnicas que estabilicen las áreas de cultivo de cacao, red...
Article
Full-text available
L’agroforesterie, qui associe des arbres aux cacaoyers, apparaît comme une option crédible pour renouveler la cacaoculture en Afrique. La culture pure de cacaoyers, dominante, y est en effet à bout de souffle. Il est donc urgent d’identifier des solutions techniques pour stabiliser les zones cacaoyères, réduire la tension sur les forêts et s’adapte...
Article
Full-text available
Manipulating plant functional diversity to improve agroecosystem multifunctionality is a central challenge of agricultural systems worldwide. In cocoa agroforestry systems (cAFS), shade trees are used to supply many services to farmers, yet their impact on soil functioning and cocoa yields is likely to vary substantially among tree species. Here, w...
Article
Conversion to organic farming can require deep technical changes that can be implemented through various pathways. This study aimed to better understand and characterize the various pathways that can be followed during conversion to organic farming. Our results highlight four types of trajectories of technical changes that depend on the number and...
Article
Full-text available
Afforestation of savannah is suggested as an approach to help addressing climate change mitigation through increased carbon (C) storage. Previous studies in Central Cameroon evidenced farmers’ ability to realize afforestation by establishing cocoa-based agroforestry systems (cAFS) on humid savannah. In this forest-savannah transition zone, we studi...
Article
Full-text available
The published on-line ms “Carbon dynamics of cocoa agroforestry systems in Central Cameroon: afforestation of savannah as a sequestration opportunity.” (https://doi.org/10.1007/s10457-017-0182-6) unfortunately bears some unit errors on soil organic C contents. © 2018 Springer Science+Business Media B.V., part of Springer Nature
Poster
Full-text available
Sensitivity analysis of the water balance simulated by WaNulCAS: a case study of complex cocoa agroforestry systems in Cameroon
Conference Paper
Full-text available
Abstract from a presentation at the 4th World Congress of Agroforestry - held in Montpellier (France) between 20-22 May 2019
Article
Full-text available
Cocoa agroforestry systems (cAFS) in Central Cameroon are established on lands which were either forest or savannah. The functioning and ecosystem services (ES) delivery of an agroecosystem can be influenced by past land-use. We hypothesised that savannah-derived cocoa agroforestry systems (S-cAFS) and forest-derived cocoa agroforestry systems (F-c...
Chapter
Full-text available
Food security, jobs, ecological transition in terms of production and consumption methods, etc, etc... agro-ecology is one way of addressing the expected challenges for humanity, and particularly farming systems in the global South. What will govern the success of the agro-ecological transition? Based on ten years' experience in the field, 130 scie...
Chapter
Pour satisfaire les besoins alimentaires et économiques des communautés rurales et urbaines en croissance, répondre à des consommateurs de plus en plus exigeants, préserver les ressources naturelles et s’adapter au changement climatique, il devient urgent de produire différemment. Pour les coordinateurs de cet ouvrage « face à l’ampleur et à l’urge...
Article
Full-text available
Cacao agroforestry systems (CAFS) can provide supporting services such as optimum light conditions for cacao growth, water and nutrient cycling and regulating services such as pest and disease control and climate regulation. This review considers recent literature on the manifestation of these services in CAFS around the world to provide an overvie...
Article
Agroforestry systems (AFS) can provide multiple ecosystem services (ES), partly due to their high (agro)biodi-versity. However, multi-criteria analyses studying trade-offs between multiple ES and exploring AFS management optimization paths are still scarce. Routine methods, such as regressions or weighted/non-weighted scorings, may reveal unsuitabl...
Article
Full-text available
Adaptation to climate change and its mitigation are some of the biggest challenges facing agriculture. In the global South, these challenges are associated with the need for food security. The arrival of climate change on the international agenda has prompted the recycling of a multitude of initiatives to address this problem, leading inevitably to...
Article
Full-text available
L’adaptation au changement climatique et son atténuation comptent parmi les principaux défis que doit relever l’agriculture. Au Sud, ces défis s’associent à un impératif de sécurité alimentaire. L’arrivée du changement climatique sur l’agenda international a favorisé le recyclage d’une multitude d’initiatives visant à y faire face avec, en corollai...
Article
Full-text available
In Africa’s main cocoa producing countries, rehabilitation of old cocoa orchards is increasingly debated but rarely adopted. In Central Cameroon, rehabilitation practices are regularly set up in old cocoa-based agroforestry systems (cAFS). To better understand the impact of such practices we built a chronosequence of 40 cAFS. We carried out specifi...
Conference Paper
Full-text available
LET'S MEET DURING THE SYMPOSIUM ! Since it moved toward-and tried to apply-intensive production patterns, cacao cultivation in Sub-Saharan Africa represents a major driver of deforestation. In Cameroon, most cacao is still cultivated in low-input traditional agroforests (CAFS). Such systems are still criticised for their presumed low cocoa produc...
Article
In Sub-Saharan Africa, cacao cultivation is a major driver of deforestation and cacao-producing countries are among the poorest in the world. Two different production schemes compete today: a “land-sharing” strategy supports cacao based agroforestry systems (cAFS) while a “land-sparing” approach advocates for the intensification of these systems. Y...
Article
Full-text available
In Central Africa, most cacao is still cultivated in low-input agroforests where cacao associated trees are traditionally valued by farmers. These systems are sustainable on the long run, support biodiversity conservation and carbon storage. Yet, little knowledge exists on the contribution of tree community management to explain such results. In Ce...
Article
Full-text available
In Central Cameroon cocoa is mainly produced by household farming systems based on complex associations between cocoa and companion trees. Setup either on native/remnant forest or savannah, these agroforestry systems (AFS) are managed according their geographical position and local pedoclimatic conditions. In this paper, we investigated the effects...
Article
Full-text available
The ability of terrestrial ecosystems to store carbon (C) under rising atmospheric CO2 will depend on how severely nitrogen (N) will limit plant growth. We tested whether increased C availability in the soil at elevated CO2 could affect N limitation by inducing N release from soil organic matter (SOM). We established microcosms composed of Holcus l...
Article
Full-text available
Changes in grassland management induce disturbances that influence both soil functioning and soil fauna. This study aimed at determining the extent to which the composition of a grassland soil nematode community could be altered by a shift of grazing regime and the potential feedback that these alterations could provoke on grassland functioning. Th...
Article
Full-text available
Soil degradation has led crop yield to decline in many Sahelian countries and is a fundamental agricultural and economical threat for local populations. In Saria, Burkina Faso, long-term experiments are being performed to find efficient soil management practices that could improve soil fertility. A randomized block experiment comprising organic ame...
Article
Full-text available
Protozoa stimulate plant growth, but we do not completely understand the underlying mechanisms, and different hypotheses seek to explain this phenomenon. To test these hypotheses, we grew the grass Yorkshire fog (Holcus lanatus) in pots with soil, which contained either (1) no organisms but bacteria – or (2) bacteria and protozoa. Half of the pots...
Article
Plant species produce litter of varying quality and differ in the quality and quantity of compounds they release from live roots, which both can induce different decomposer growth in the soil. To test whether differences in decomposer growth can forecast the amount of N species acquire from plant litter, as suggested by theory, we grew individuals...
Article
Full-text available
Legume–grass interactions have a great influence on grassland primary production and it was recently shown how defoliation of a legume can increase the transfer of fixed N to a neighbouring grass. It has also been shown that defoliation of a plant can increase soil microbial activity and lead to better soil N availability in the rhizosphere of the...
Article
It is known that plant species can induce development of different soil decomposer communities and that they differ in their influence on organic matter decomposition and N mineralization in soil. However, no study has so far assessed whether these two observations are related to each other. Based on the hypothesis that root-induced growth of soil...
Article
Plant species differ in their effects on ecosystem productivity and it is recognised that these effects are partly due to plant species-specific influences on soil processes. Until recently, however, not much attention was given to the potential role played by soil biota in these species-specific effects. While soil decomposers are responsible for...

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